Cylinder head and method of making the same



July 25., 1939. TJAARDA 2,167,093

CYLINDER HEAD AND METHOD OF MAKING THE SAME I Filed D60. 7, 1956 I 2 Sheet's-Sheet 1 3 Iii-E INVENTOR. J'oinz 2744744.

ATTORNEYS.

July 25, 1939. J, TJAARDA CYLINDER HEAD AND METHOD OF MAKING SAME 2 Sheets-Sheet 2 Filed Dec. 7, 1936 4 INVENTOR J' fi 7j'aarda'. M

Patented July 25, 1939 UNITED STATES PATENT OFFICE John Tjaarda, Birmingham, Mich., assignor to Briggs Manufacturing Company, Detroit, Mich., a corporation of Michigan Application December 7, 1936, Serial No. 114,614

4 Claims.

not exclusively, to composite cylinder heads for internal combustion engines and especially to a head made of a cast base plate and a pressed sheet metal cover or water jacket. The invention in one of its aspects also comprises the method of manufacturing such composite cylinder head.

It is commonly appreciated in the art that numerous advantages may be obtained if cylinder heads for internal combustion engines are not made as cast,units but are built up of a cast iron base plate and a pressed sheet metal cover secured together to provide the necessary space for circulation of the cooling water. Some of such advantages are: A much lighter cylinder head, a decrease in the cost of manufacture, and a better control of carbon deposits within the combustion chamber. Therefore, numerous attempts have been made to produce such a composite head in order to secure the advantages possessed thereby.

However, great difiiculties have heretofore been encountered in providing a cylinder head of the above character which would not leak in places of juncture of the base plate and the sheet metal cover, and particularly in junctures thereof at the spark plug nests. Said difficulties have resulted primarily from the fact that it is impractical to secure a pressed metal jacket to a cast base plate by welding; since the same are ordinarily made of different metals. Welding together a sheet steel cover and a cast iron base plate involves many technical difliculties; and ordinarily no water-tight joint can be produced in such cases by Welding. While at the places where studs pierce through the cylinder head, the required tightness of the joints may be attained by the pressure of the nuts on the pressed steel cover supported around the studs by suitable bosses, the spark plugs cannot be called upon to exert a suificiently high pressure on the cover and, therefore, some other means have to be provided at the spark plug nests to insure the necessary tightness of the joints thereat.

One of the objects of the present invention is to overcome the foregoing difiiculties and to provide an improved composite cylinder head having water-tight joints at the spark plug nests, said joints capable of being produced by stamping operations.

Another object of the invention is to provide a method for making a water-tight joint at the places of juncture of a steel sheet and a cast iron plate.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein This invention relates particularly, although.

like reference characters designate corresponding parts in the several views.

In the drawings:

Fig. 1 is a transverse vertical sectional view of the cylinder head embodying the present invention, the same being shown secured at the cylinder block of an internal combustion engine.

Fig. 2 is an enlarged sectional view of the spark plug nest.

Fig. 3 illustrates the first step in fabricating my improved joint in accordance with the invention.

Fig. 4 illustrates the second step of fabricating the joint.

Fig. 5 shows the spark plug nest completed in accordance with the last step of my improved method.

Fig. 6 is a plan view of the cylinder head emtion is not limited in its application to the details of constructon and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawings there is shown, by way of example, the upper portion of a cylinder of an internal combustion engine with a detachable composite cylinder head including the watertight joint embodying the invention.

Referring more particularly to the drawings, the numeral 10 represents a cylinder block of-an ordinary internal combustion engine having a cylinder II and a piston l2 reciprocable therein. The numeral l3 indicates a poppet valve fitted into a seat 14, the valve intended to control the intake of the engine. A composite cylinder head indicated generally by the numeral is secured to said cylinder block l0, a gasket l6 being interposed between the head and the cylinder block. The head I5 comprises generally a cast iron base plate I! shaped to provide a combustion chamber i8 and flanges l9 and engaging the milled surfaces of the cylinder block. On said plate I! there are integrally formed a number of stud bosses 2| having drilled holes for the passage of the studs 22, and a number of spark plug bosses 23, each of them adapted to receive a spark plug 24 held in a tapped hole 25 and partially surrounded by a counterbore 26. A gasket 24a is interposed between the spark plug 24 and the plate in order to insure tightness of the joint. The base plate i1 is preferably cast with an insert of sheet metal, preferably sheet steel, forming a peripheral flange 21 which extends outwardly and beyond and continuously around the periphery of the base plate l'l.

A' pressed cover 26 made preferably of sheet steel is suitably shaped to provide the water space 26. A depending surrounding flange 36 integrally attached to the cover extends contin uously around said cover and is provided with an outwardly extending flange 3| adapted to engage the flange 21 embedded in the plate H. The flanges lland 21 are continuously welded to provide a water-tight joint and to effect a rigid connection of the cover 26 to the base plate II. A number ofholes 22 are provided in said cover 26 for passage of the studs 22, said holes registering with the holes drilled in the bosses 2|. Around said holes there are provided embossments 22 partially surrounding said stud holes and stiffening the edges of the cover 26 around said holes.

For securing the cover 26 to the plate I! at the spark plug nests there is provided on said cover 26 a depending flange :4 adapted to flt the counterbore 26 provided in the spark plug boss 22. A groove 36 is formed on the cylindrical surface of the counterbore 26, said groove adapted to receive the bead Ila formed on the flange 26 by outward pressure, said bead tightly en gaging said groove II.

It is an important feature of my invention that there are provided means for supporting the flange 26 engaging the plate l1 and preventing contraction of said flange because of its elasticity after the expanding member is removed. In the present embodimentof the invention said means are exemplified by a cylindrical insert 26 adapted to flt into the cylindrical space formed by the flange 34, said'insert being expanded therein for locking the flange 26 in the bore 26. Said insert is permanently left in the spark plug nest and constitutes a part of the joint, its function being to expand said flange 24 into engagement with the bored cylindrical surface 26 and to sup rt said flange 34 from inside of the nest, thereby preventing separation of the surfaces of contact, which separation may destroy. the watertightness of the Joint.

In accordance with the invention there is provided, a method 01' fabricating the water-tight joint by stamping operations. The flrst step of my method illustrated in Fig. 3 includes. fltting the flange 36 into the bore 26 of the stud 23 and fitting the insert 36 into the cylindrical space formed by said flange 64. The second step of iny method comprises expanding outwardly the insert 36 by applying a longitudinal pressuretheretol I prefer to eii'ect such outward expanding of the insert 36 by striking or pressing the,

of the properly selected length of the insert 36,

the upper edges ofsaid insert are partly upset.

and partly bent outwardly therebyproducing an upset flange 66b which increases the locking effect produced by said insert. The plate ll is supported during the above operation by a pad 38 in order to prevent breakage. The flnished joint is shown in Fig. 5,, said flgure clearly showing the shape which is assumed by the flange 24 and the insert 36 after said insert 26 has been operated upon as described. In sane instances,

it may be advantageous to expand the insert it with the aid of a suitable roller.

Thus, in one of its broader aspects my lnvention contemplates an improved fluid tight Joint between a bulk metal section such as a cast or a forged member and a sheet metal part, which joint includes a bore in said bulk section and a flange on said sheet metal part, said flange being expanded by means of a member locking said flangeto said bore and supporting said flange.

Considered from another of its broader aspects my invention comprehends providing a method of fabricating such joint by spreading or expanding outwardly in said bore a cylindrical insert by applying a longitudinal pressure to such an v insert.

' I claim: I

1. In a cylinder head made of a base plate and a pressed sheet cover, a water-tight joint com-,

prising a boss formed on said plate, said boss being provided with a bore, a cylindrical flange formed on said cover and fltted into said bore:

and an insert fitted into the cylindrical space therein to cause said flange to engage directly and positively said base plate and to be locked in said bore.

3, A composite cylinder head made of a cast base plate and a pressed sheet cover, said head including a water-tight joint comprising a boss formed integrally on said plate, said boss being provided with a grooved bore; a cylindrical flange formed on said cover and fitted into said bore; and a cylindrical insert fitted into the cylindrical space formed by said flange and outwardly expanded therein for locking said flange in said bore to said base plate directly and positively.

4. A composite cylinderhead i'oran internal combustion engine, said head made of a cast base plate and a pressed sheet metal cover and including a spark plug nest, said nest comprising a boss integrally formed on said plate, said boss being provided with a grooved bore; a cylindrical flange formed on said cover and fitted into said bore; and a cylindrical insert fltted into the cylindrical space formed by said flange'and outwardly expanded therein for locking said flange in said bore directly and positively to said base plate.

JOHN TJAARDA. 

